But David Kaye, the UN's special rapporteur on the promotion and protection on the rights to freedom of opinion and expression, has now urged politicians to reconsider, as the proposal could be in breach of "international law."

A series of bans on pornographic content available to the public have been implemented by the Tory government since taking office.

Depictions of sexual acts such as spanking, face-sitting and female ejaculation are now banned in British porn, and internet providers could be hit with fines if they fail to block websites identified by the British Board of Film Classification (BBFC) as contravening the law.

Age verification checks will be made compulsory by amendments to the new Digital Economy Bill, which is currently being examined by the House of Lords.

"Proportionality is in the eye of the beholder but it's clear there is a benefit to children in introducing these measures. States are under an obligation to protect children from this kind of harmful material - that's what the government is doing."